Abstrakt

Grandstands are types of structures commonly used during sport events or music concerts. Dynamic loads generated by crowd movement may have significant influence on human perception as well as may lead to the destruction of a structure. Lighter and more slender structural steel members are more easily excitable by spectators. If the synchronized movement is tuned with the natural frequency of the affected part of the structure, resonance might occur. A large number of accidents involving the collapse of temporary grandstands, during different types of events, has been observed in the past. More than 100 people were injured after a seating section gave way during a car race in Brazil in 2010. The collapse of a grandstand in Corsica in 1992 hurt thousands of people and resulted in several fatalities. Dynamic loads are often found to be the most important ones at the design stage of civil engineering structures. Safety and serviceability of these structures may need to be checked. In this paper, an idea of using polymer dampers, in order to reduce steel grandstand vibrations under dynamic loads, is proposed. The polymer mass is a specially designed flexible two-component grout, which is based on polyurethane resin. It has been proven that this kind of material has also additional damping properties [6]. A numerical analysis of a temporary steel grandstand has been conducted and dynamic parameters have been estimated. Four different models have been considered. Two of them describe a standard steel temporary structure (empty and occupied). In the second two models, polymer dampers (in the form of strips) have been added as a proposed method of reduction of structural vibrations. Numerical analysis has been conducted for all cases and behaviour of a steel grandstand under dynamic crowd load has been determined.

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